We developed the isolation method of alpha-1-acid glycoprotein (AAG).AAG concentration in serum became hightest at 4th day after acute myocardial infarction and became to the original level in 2 weeks.Binding of disopyramide, which bind to AAG,was lowest at the 4th day and returnd to the original level in 2 weeks.Then we compared the protein binding characteristics of disopyramide for the isolated AAG of the 4th day and of 4th week.There was no change in dissociation constant between them.However, the number of binding sites was lower in 4th day AAG compared to 4th week one.We also measured the concentration of sugers of AAG.There was no change in fucose concentration between them.However, the concentrations of N-acetylglucosamin, galactose, mannose and N-acetylneuramic acid were higher in 4th day AAG compared to 4th week one.We concluded the constitutional change of AAG influenced the protein binding of the drug.